Abstract:Wave energy conversion has an essential difference from other renewable energies since the dependence between the devices design and the energy resource is stronger. Dimensioning is therefore considered a key stage when a design project of Wave Energy Converters (WEC) is undertaken. Location, WEC concept, Power Take-Off (PTO) type, control strategy and hydrodynamic resonance considerations are some of the critical aspects to take into account to achieve a good performance. The paper proposes an automatic dimensioning methodology to be accomplished at the initial design project stages and the following elements are described to carry out the study: an optimization design algorithm, its objective functions and restrictions, a PTO model, as well as a procedure to evaluate the WEC energy production. After that, a parametric analysis is included considering different combinations of the key parameters previously introduced. A variety of study cases are analysed from the point of view of energy production for different design-parameters and all of them are compared with a reference case. Finally, a discussion is presented based on the results obtained, and some recommendations to face the WEC design stage are given.

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There are many types of electrical machines suitable for electric vehicles. Nowadays, most manufacturers and researchers tend towards two major alternatives: permanent magnet synchronous machines and induction machines. However, these are not the only competitive candidates. Reluctance machines, which have been well-known for some decades already, present some interesting advantages. For instance, switched reluctance machines are intrinsically redundant and fault-tolerant, which makes them attractive for applications in which robustness is compulsory. In this sense, switched reluctance drives can keep working even when one of their phases loses its functionality for any reason. In an electric vehicle, this would mean being able to keep driving the vehicle even after some failures, although with reduced performance (in degraded mode). In this chapter, switched reluctance drives for traction applications are analyzed, focusing on their capability to operate in degraded mode (with m-1 phases available).

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One of the big issues ocean‐wave energy faces nowadays is the oscillation of the generated power. Among others, energy storage is a solution that has been widely proposed and validated for an adequate grid or isolated load integration. However, the unpredictability of ocean waves may pose a challenge when specifying the energy storage system (ESS) technology and specifications, especially in the case of stand‐alone operation. This study presents a suitable methodology for the design of a certain wave energy converter (WEC) and the calculation of a certain stochastic model of the latter necessary for the subsequent sizing of the ESS. As a result, the storage system is defined in terms of energy, power and type of technology for the specific WEC and chosen location. The problem is accomplished in this study describing systematically the method and solving a particular example of the design of a wave converter in the Gulf of Mexico.

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This paper focuses on Hybrid Energy Storage Systems (HESS), consisting of a combination of batteries and Electric Double Layer Capacitors (EDLC), for electric urban busses. The aim of the paper is to develop a methodology to determine the hybridization percentage that allows the electric bus to work with the highest efficiency while reducing battery aging, depending on the chosen topology, control strategy, and driving cycle. Three power electronic topologies are qualitatively analyzed based on different criteria, with the topology selected as the favorite being analyzed in detail. The whole system under study is comprised of the following elements: a battery pack (LiFePO4 batteries), an EDLC pack, up to two DC-DC converters (depending on the topology), and an equivalent load, which behaves as an electric bus drive (including motion resistances and inertia). Mathematical models for the battery, EDLCs, DC-DC converter, and the vehicle itself are developed for this analysis. The methodology presented in this work, as the main scientific contribution, considers performance variation (energy efficiency and battery aging) and hybridization percentage (ratio between batteries and EDLCs, defined in terms of mass), using a power load profile based on standard driving cycles. The results state that there is a hybridization percentage that increases energy efficiency and reduces battery aging, maximizing the economic benefits of the vehicle, for every combination of topology, type of storage device, control strategy, and driving cycle.